The present invention pertains to analog and digital CCIS data transmission and more particularly to terminal equipment control circuitry adaptable for use with modems and digital trunks.
Various kinds of terminal equipment may be employed to transmit CCIS data between switching offices. This terminal equipment may include modems, digital trunks or Tl spans. Typically, different terminal equipment control circuits were designed to control one particular kind of terminal equipment. Problems associated with this design or lack of commonality and excessive real time usage of the associated CPU.
One method of alleviating the real time problem of the CPU is to build a separate terminal equipment control circuit for each type of terminal equipment being operated. This is wasteful in design and also in the amount of space and components required to assemble such circuitry. Commonality of circuitry is, therefore, highly desirable.
One CCIS circuit arrangement possessing a degree of commonality is taught by U.S. Pat. No. 4,464,748 issued on Aug. 7, 1984, to K. A. Krikor. The assignee of the present application is the successor and all right, title and interest to the assignee of the above mentioned U.S. patent.
Accordingly, it is an object of the present invention to provide common circuitry for analog and digital CCIS data transmission and reception.